Added "long_about"

src/cli.rs

@@ -4,7 +4,8 @@ use clap::Parser;
 use clap::ValueEnum;
 
 #[derive(Parser, Debug)]
-#[command(version, about, long_about = None)]
+#[command(version, about, long_about= "A compression utility for utf-8 encoded text, \
+    using only basic canonical huffman encoding.")]
 pub struct Args {
 
     /// input file